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# FDA Orders Takeda to Add Boxed Warning to Adzynma
- URL: https://www.fdaweb.com/fda-orders-takeda-to-add-boxed-warning-to-adzynma/
- Published: 2026-06-02T12:00:00.000Z
- Updated: 2026-09-14T13:40:19.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5161246

FDA has ordered Takeda Pharmaceuticals to strengthen the safety labeling for its rare disease therapy Adzynma, including the addition of a Boxed Warning, after the agency and the company failed to reach agreement on how to address concerns about potentially life-threatening immune reactions.

In a just-posted [5/20 letter](https://www.fda.gov/media/192821/download?attachment=&utm%5Fmedium=email&utm%5Fsource=govdelivery), FDA said it was exercising its authority under Section 505(o)(4) of the Federal Food, Drug, and Cosmetic Act to require safety-related labeling changes for Adzynma, a recombinant ADAMTS13 product for treating congenital thrombotic thrombocytopenic purpura (cTTP).

The agency's action stems from what it described as new postmarketing safety information showing that some patients may develop neutralizing antibodies against ADAMTS13 after treatment. According to FDA, these antibodies have been associated with serious outcomes, including death.

The dispute follows a 2/5 safety labeling notification in which FDA directed Takeda to submit revised labeling addressing the risk. Takeda responded on 3/6 with a prior approval supplement proposing changes to the product's prescribing information.

FDA officials said they reviewed the submission and entered into discussions with the company The agency extended the statutory discussion period in April while the two sides attempted to reach agreement on the language. However, FDA ultimately concluded that Takeda's proposed revisions did not adequately address the newly identified safety concerns.

As a result, the agency issued a formal order requiring Takeda to implement labeling changes specified in the February notification and subsequent FDA communications. Those changes include the addition of a Boxed Warning, as well as revisions to the warnings and precautions section and the clinical pharmacology section of the prescribing information.

FDA directed Takeda to submit a "changes being effected" supplement containing the required labeling revisions by 6/4.

In the correspondence, FDA also reminded the company that failure to comply with the order could result in civil monetary penalties and cause the product to be deemed misbranded under federal law. Additional enforcement actions, including product seizure or injunction, could also be pursued.

Late last year, FDA said it was investigating the death of a pediatric patient with cTTP who developed neutralizing antibodies to the enzyme ADAMTS13 after treatment with Adzynma. It also issued a [safety communication](https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/fda-investigating-death-due-neutralizing-antibodies-adamts13-following-adzynma-treatment-congenital?ref=fdaweb.com).